Role of stem cells in maxillary sinus floor augmentation: meta-analysis of randomized controlled trials

The aim of this systematic review was to compare the effectiveness of stem cell-based grafts versus conventional bone graft materials in maxillary sinus floor augmentation. A comprehensive literature search was conducted across Scopus, Cochrane, Embase, Web of Science, and Wiley Online Library, and was supplemented by manual searches in Google Scholar, the gray literature, and reference lists, following PRISMA 2020 and Cochrane guidelines. Fifteen randomized controlled trials involving 205 patients met the inclusion criteria. Meta-analysis revealed no significant difference in implant survival between the groups (P > 0.05). Histomorphometric outcomes, particularly new bone formation, significantly favored the stem cell-based grafts group, especially at 6 months (new bone formation at 6 months, P = 0.022). The stem cell-based grafts group also exhibited significantly lower residual graft content at 6 months (P = 0.008), while the control group showed increased marrow space. Imaging parameters (bone height, volume, density, and marginal bone loss) tended to favor the control group; however, the small number of studies reporting radiographic outcomes limits interpretability. Overall, stem cell-based grafts appear to lead to increased new bone formation when compared to conventional grafts, although they do not significantly improve implant survival. Further high-quality studies are needed to clarify radiographic and tomographic outcomes.